CWE-338 - Use of Cryptographically Weak Pseudo-Random Number Generator (PRNG)

CWE ID:

CWE-338

Medium

Abstraction:Base
Structure:Simple
Status:Draft

Release Date:2006-07-19
Latest Modification Date:2023-10-26

Weakness Name

Use of Cryptographically Weak Pseudo-Random Number Generator (PRNG)

Description

The product uses a Pseudo-Random Number Generator (PRNG) in a security context, but the PRNG's algorithm is not cryptographically strong.

When a non-cryptographic PRNG is used in a cryptographic context, it can expose the cryptography to certain types of attacks. Often a pseudo-random number generator (PRNG) is not designed for cryptography. Sometimes a mediocre source of randomness is sufficient or preferable for algorithms that use random numbers. Weak generators generally take less processing power and/or do not use the precious, finite, entropy sources on a system. While such PRNGs might have very useful features, these same features could be used to break the cryptography.

Common Consequences

Scope: Access Control

Impact: Bypass Protection Mechanism

Notes: If a PRNG is used for authentication and authorization, such as a session ID or a seed for generating a cryptographic key, then an attacker may be able to easily guess the ID or cryptographic key and gain access to restricted functionality.